The present invention relates to semiconductor processing, and more particularly to a support tape for use in the processing of a semiconductor wafer.
Semiconductor device die are usually formed in a relatively large wafer (e.g. six inches in diameter), and then singulated from the wafer by sawing or the like.
In some cases, the wafers are relatively thick (e.g. 300 microns or more), and can be conveniently handled without breakage by processing tools such as ion implanters, photolithography tools, etching and cleaning equipment, metal deposition and insulation deposition equipment and the like.
It is known that in some cases, the characteristics of the semiconductor device can be improved if the wafer is thinned to, for example, below 250 microns, or even 100 microns or less. Also, it is known that it may be economical to form certain semiconductor devices in float zone type wafers and then thin the wafer to obtain thin semiconductor devices.
Wafers can be thinned by back grinding after the major wafer processing steps are completed. For example, wafers can be thinned to 80 microns or less after the top surface processing has been completed. For example, after the top surface processing is completed, a flexible tape is adhered to the processed front side of the wafer and the back side is suitably ground to the desired thickness. The flexible tape may be a plastic film of the kind commercially known as backgrind tape, which holds the wafer during the thinning process. The backgrind tape is peelable from the wafer.
In the case of thinned wafers, as the wafer is thinned it loses rigidity. Thus, it becomes difficult to handle the wafer. For example, it becomes difficult to remove the wafer from the grinding system without breaking the wafer. Excessive breakage negatively affects the yield and adversely affects any cost savings that may have been achieved by the wafer thinning method.
To overcome the problem, the prior art has suggested either using a more rigid carrier backing or a rigid carrier. A more rigid backing, however, does not bend or fold easily, making it difficult to remove from the thinned wafer without causing damage to the same. Also, rigid carriers are more complex to use since the carrier must be attached with an adhesive and will be very hard to remove without consequent damage to the thinned wafer.